Photosynthetic and bacterial production gradients in a larval fish nursery:the St. Lawrence River transition zone

Vincent, WF; Dodson, JJ; Bertrand, Normand; Jj, Frenette

doi:10.3354/meps139227

Cited by 40 publications

(50 citation statements)

References 17 publications

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“…WC used bacterial concentrations, average water column depths, an average observed growth rate of 0.047 h-l (Table 3), and an assumed carbon content of 25 fg C cell-l (Bell 1993) to obtain bacterial production estimates of 580, 300, 210, and 230 mg C m-2 d-l for boxes 2, 3,4, and 5. Thymidine uptake measurements in the same area yielded similar values (150-310 mg C m-2 d-l; Vincent et al 1996). The box model shows that there is a small imbalance between growth and grazing, with the coefficient r giving the magnitude of the imbalance (Table 4).…”

Section: Resultssupporting

confidence: 52%

“…Such concentrations are in the low range of values reported by Ducklow and Shiah (1993) for estuarine waters, where bacteria often reach concentrations > lOlo liter-l, but are in the range of values reported by Vincent et al (1996) in the same area. Plotting bacterial abundance against salinity reveals an exponential decrease between salinity 0 and 30 (Fig.…”

Section: Resultsmentioning

confidence: 59%

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Bacterial dynamics in the upper St. Lawrence estuary

Painchaud

Lefaivre²,

Therriault³

et al. 1996

Limnology & Oceanography

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The distribution of free bacteria in the St. Lawrence estuary was interpreted by means of bacterial fluxes and hydrodynamic residence times, derived from a circulation model, and growth and grazing rates, obtained from cultures. Bacterial abundances decreased exponentially along the salinity gradient, from 3.9 x lo9 liter-' in freshwater to 0.5 x lo9 liter-l at salinity ~20. The rates of growth (0.02-0.08 h-l) and grazing (0.0 l-O.09 h-l) were strongly correlated (r = 0.82), which suggests that bacteria tended toward a state of trophodynamic equilibrium (growth E grazing). However, negative bacterial fluxes obtained from the model imply that the estuary is a sink for bacteria. Results from the circulation model and the cultures show that physical processes are important controlling factors of the distribution of bacteria and point IO predation as the process causing bacterial losses in the estuary. Calculations show that small imbalances between growth and grazing can account for the observed distribution.Rates of dispersion and growth and grazing are of the same order of magnitude, which shows that biological processes are nevertheless significant relative to physical processes. Although the distribution of free bacteria appears largely under hydrodynamic control, the bacterial community is characterized by significant biological rates and can experience large transformations during estuarine transit.

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Section: Resultssupporting

confidence: 52%

Section: Resultsmentioning

confidence: 59%

Bacterial dynamics in the upper St. Lawrence estuary

Painchaud

Lefaivre²,

Therriault³

et al. 1996

Limnology & Oceanography

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“…In tropical ecosystems, at coastal environments in the south of Brazil, Cesar and Abreu (2001) ). On the other hand, PPP values were lower relative to other studies carried out in temperate rivers (Goosen et al, 1999;Vicent et al, 1996). Despite the high variability in BSP and PPP results, seasons did not affect the values of both processes.…”

Section: Discussioncontrasting

confidence: 44%

“…In the Ipanema river, the most eutrophic habitat, BSP was considerably high compared with data from temperate lakes and rivers (Goosen et al, 1999;Vicent et al, 1996;Vrede, 1996;Le et al, 1994). In tropical ecosystems, at coastal environments in the south of Brazil, Cesar and Abreu (2001) ).…”

Section: Discussionmentioning

confidence: 96%

Bacteria and phytoplankton production rates in eight river stretches of the middle Rio Doce hidrographic basin (southeast Brazil)

Petrucio

Barbosa

Thomaz

2005

Braz. arch. biol. technol.

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Measurements of bacterial secondary production (BSP), together with primary phytoplanktonic production (PPP) were conducted during dry and rainy seasons, in eight rivers of different orders submitted to different degrees of human impacts (different trophic degree). We aimed to determine and compare the importance of BSP and PPP in carbon fixation in these different lotic ecosystems.Our results showed that the Ipanema River was the most modified system by anthropogenic effluents inputs. These inputs altered the trophic degree and BSP rates of these streams and rivers.

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“…Some filter clogging could have resulted in an underestimation of uptake rates by freeliving prokaryotes; however, the samples flowed rapidly through the 3 µm filters under low pressure, suggesting that any such effects were minimal. A high proportion of bacterial production associated with particles has been recorded in several other river-influenced systems, including the estuarine turbidity zones of the St. Lawrence River (Vincent et al 1996) and the Columbia River (Crump & Baross 2000b). Archaea have been detected in marine arctic sediments (Ravenschlag et al 2001), and therefore another potential source of these microorganisms to the water column would be the resuspension of bottom sediments caused by wind-induced mixing or by the coastal upwelling observed during the sampling period.…”

Section: Discussionmentioning

confidence: 99%

Prokaryotic community structure and heterotrophic production in a river-influenced coastal arctic ecosystem

Garneau

Vincent²,

Alonso‐Sáez³

et al. 2006

Aquat. Microb. Ecol.

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131

105

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Spatial patterns in prokaryotic biodiversity and production were assessed in the Mackenzie shelf region of the Beaufort Sea during open-water conditions. The sampling transect extended 350 km northwards, from upstream freshwater sites in the Mackenzie River to coastal and offshore sites, towards the edge of the perennial arctic ice pack. The analyses revealed strong gradients in community structure and prokaryotic cell concentrations, both of which correlated with salinity. Picocyanobacterial abundance was low (10 2 to 10 3 cells ml -1 ), particularly at the offshore stations that were least influenced by the river plume. Analysis by catalyzed reporter deposition for fluorescence in situ hybridization (CARD-FISH) showed that the dominant heterotrophic cell types were β-Proteobacteria at river sites, shifting to dominance by α-Proteobacteria offshore. Cells in the Cytophaga-Flavobacter-Bacteroides and γ-Proteobacteria groups each contributed < 5% of total counts in the river, but >10% of counts in the marine samples. Archaea were detected among the surface-water microbiota, contributing on average 1.3% of the total DAPI counts in marine samples, but 6.0% in turbid coastal and riverine waters. 3 H-leucine uptake rates were significantly higher at 2 stations influenced by the river (1.5 pmol l -1 h -1 ) than at other marine stations or in the river itself (≤0.5 pmol -1 h -1 ). Size-fractionation experiments at 2 coastal sites showed that > 65% of heterotrophic production was associated with particles > 3 µm. These results indicate the importance of particleattached prokaryotes, and imply a broad functional diversity of heterotrophic microbes that likely facilitates breakdown of the heterogeneous dissolved and particulate terrestrial materials discharged into arctic seas. KEY WORDS:Prokaryote diversity · Archaea · Proteobacteria · Cytophaga-FlavobacterBacteroides · Arctic Ocean · Mackenzie River estuary · Picocyanobacteria · CARD-FISH Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 42: [27][28][29][30][31][32][33][34][35][36][37][38][39][40] 2006 ments (Payette et al. 2004) may mobilize the large stocks of organic carbon contained within their soils and cause increased transfer of these materials to arctic rivers and ultimately to the ocean. Heterotrophic microbiota are likely to play a major role in the response of coastal arctic ecosystems to ongoing change, but prokaryotic diversity and production in these cold ocean environments have been little explored (Amon 2004).In the western Canadian Arctic, the Mackenzie River discharges large quantities of freshwater, solutes and sediments into a vast shelf region of the Beaufort Sea that extends >100 km offshore and encompasses a total area of 63 600 km 2 (Carmack et al. 2004). The annual discharge of the Mackenzie River (330 km 3 yr -1 ; Macdonald et al. 1998) is the 4th highest in the Arctic Basin after the Siberian rivers Yenisei, Lena and Ob, with concomitantly large inputs of freshwater biota, terrestria...

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Photosynthetic and bacterial production gradients in a larval fish nursery:the St. Lawrence River transition zone

Cited by 40 publications

References 17 publications

Bacterial dynamics in the upper St. Lawrence estuary

Bacterial dynamics in the upper St. Lawrence estuary

Bacteria and phytoplankton production rates in eight river stretches of the middle Rio Doce hidrographic basin (southeast Brazil)

Prokaryotic community structure and heterotrophic production in a river-influenced coastal arctic ecosystem

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